The present invention is directed, in general, to communication devices and, more specifically, to methods of manufacturing and integrating monolithic optical devices.
Optical fibers are key components in modern telecommunications and have gained wide acceptance. As is well known, telecommunication optical fibers are thin strands of glass capable of transmitting an optical signal containing a large amount of information over long distances with very low loss. Single fibers can carry multiple packets of data that are multiplexed on the fiber either by time division, where different slots of time are allocated to different packets, or by wavelenth division multiplexing, where different wavelengths are allocated for different data. Optical devices, such as modulators and switches, perform the important function of adding information content to optical signals in optical communications systems. Such devices may include expitaxially grown multi-quantum well type structures of an indium phosphide or indium gallium arsenide phosphide (InGaAsP) base. The quantum well type structures may be undoped, or may be doped with various n-type and p-type dopants.
Traditionally, the optical industry focused on hybrid integration of optical devices, wherein many optical devices are manufactured on individual optical substrates, all of which are subsequently connected by optical fibers. Hybrid integration was sufficient for traditional telecommunication devices. However, with the current increased demand for reliably carrying increased amounts of data, hybrid integration is problematic. Specifically, hybrid integration may experience poor optical coupling between the optical devices and the optical fiber, poor mechanical stability of the circuit, high cost, and low performance. Thus, in an attempt to circumvent some of the problems associated with hybrid integration, the current trend in the optical industry is to manufacture multiple optical devices on a single optical substrate. Manufacturing multiple optical devices on a single optical substrate, or so-called monolithic integration, is the ultimate solution to the problems discussed above. However, current manufacturing techniques each have problems associated therewith.
One manufacturing technique currently used to monolithically integrate multiple devices on a single optical substrate is called the xe2x80x9cbutt jointxe2x80x9d technique. The butt joint technique typically consists of growing a first device structure, for example a laser, on the whole wafer, followed by selective etching and regrowth of an area not protected by a mask layer, and representing a second device. The butt joint technique currently allows for independent design of different devices and is used by many manufacturers. However, it commonly experiences certain problems at the junction between the first and second devices.
Because the second device typically grows substantially uniformly along all crystallographic planes, significant overgrowth occurs proximate the junction between the first and second device. Such overgrowth produces variations in the thickness of the second device or layers thereof. The overgrowth can also result in nonuniformity of material composition, for example of strain or inflection wavelength (see FIG. 2) across the second device. This is indicative of nonuniformity of molecular and/or crystalline structure. Accordingly, the butt joint technique may cause edge effect and material quality issues at the junction, as well as dislocations at the junction that may produce optical losses via absorption. The variations in molecular and crystalline structure at the junction between the first and second devices also contribute to poor optical coupling therebetween, high cost, low reliability, low yield and low performance of the integrated device.
Accordingly, what is needed in the art is a method to monolithically integrate multiple optical devices on a single optical substrate that does not experience the difficulties and problems associated with the prior art methods.
To address the above-discussed deficiencies of the prior art, the present invention provides methods of manufacturing and integrating optical devices. In one embodiment, a method of integrating an optical device may include forming a first device over a substrate, and forming a second device over the substrate and adjacent the first device with a deposition gas having an etchant selective to a deposited component of the deposition gas.
The foregoing has outlined an embodiment of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.